The present invention relates to a flare manufacturing method and flare manufacturing apparatus for bulbs such as incandescent, fluorescent lamps or the like.
A configuration of a flare manufacturing machine for use in a flare manufacturing method for conventional bulbs, for example, incandescent and fluorescent lamps will be described with reference to FIG. 9.
Rotating heads 52 each including a chuck mechanism 52a for chucking an outer peripheral portion of a glass bulb 51 are mounted on an index plate 53 using a number of head screws 52b. The rotating head 52 can be rotated by a drive motor 54 in an arrow I direction. In addition, the drive motor 54 has a mechanism for intermittently feeding the index plate 53 depending on the rotation speed of the rotating heads 52, and rotates in an arrow J direction. A base 55 has a glass bulb positioning jaw 57 that is operated by an air cylinder 56 to chuck a tip portion of the glass bulb 51 and that can be moved in arrow K and L directions. A glass bulb positioning base 58 is operated by an air cylinder 59 for movement in arrow M and N directions. A molding plate 61, which forms a flare shape when rotated by a molding motor 60, is attached to the molding motor 60 via a molding shaft 61a. Besides, the molding plate 61 is attached to the molding motor 60 for rotation in an arrow O direction and for movement by a molding cylinder 62 in arrow P and Q directions. Reference numeral 63 denotes a burner for heating a peripheral portion of the glass bulb 51. In addition, the base 55 has a burner 63 attached to the base 55 for heating the glass bulb 51 after the flare shape has been formed, as also shown in FIG. 10, and a bulb cutter 64 also attached to the base 55 for cutting the glass bulb 51 into predetermined sizes.
A process for manufacturing a flare using a conventional bulb flare manufacturing machine of the above described configuration will be described.
First, in a first position, an automatic insertion machine (not shown) inserts the glass bulb 51 into the rotating head, and the glass bulb positioning jaw 57 chucks the glass bulb 51 and moves it in the arrow K direction. Then, a glass bulb positioning base 58 moves in an arrow N direction and then stops at a predetermined position to abut on the tip portion of the glass bulb 51 in order to establish a predetermined length size. Then, the chuck mechanism 52a chucks the outer peripheral portion of the glass bulb 51, and the glass bulb positioning jaw 57 stops chucking and then moves in the arrow L direction. The glass bulb positioning base 58 also moves in an arrow M direction to leave the glass bulb 51. Next, upon detecting the insertion of the glass bulb 51, the rotating head 52 starts rotating in the arrow I direction.
In a second position, the burner 63 gradually heats the peripheral portion of the tip of the glass bulb 51 until the glass bulb reaches its softening point.
In a third position, the molding plate 61 is moved in the arrow Q direction and is inserted slowly into the inside of the tip portion of the glass bulb 51. Then, the rotating force of the molding plate 61 causes the glass bulb 51 to gradually expand starting with its tip portion along the molding plate 61. The molding plate 61 is further inserted and then stopped at a predetermined position. Then, the glass bulb 51 is deformed into a flare shape entirely corresponding to the shape of the molding plate 61, and the molding plate 61 moves in the arrow P direction.
Subsequently, the burner 63 heats the glass bulb 51 in a fourth position, and the bulb cutter 64 cuts the glass bulb 51 in a fifth position to complete flare manufacturing.
According to such a conventional flare manufacturing method for bulbs, the outer peripheral portion of the glass bulb is chucked to mold the bulb into a flare shape by defining this shape from inside of the glass bulb. The glass bulb, however, is not externally molded during the formation of the flare shape, resulting in large variations in dimensional accuracy such as the outer-diameter accuracy and roundness of the flare and the concentricity between the bulb portion and the flare portion.
It is an object of the present invention to provide a flare manufacturing method and apparatus for bulbs which can obtain a flare with a stable dimensional accuracy.
A flare manufacturing method for bulbs according to the present invention comprises: a cylindrical bulb; heating means for heating and melting the bulb; a first mold having a recess formed into a flare shape and rotatively moved by rotation drive means; and a second mold having a projection fitted in the first mold to form a flare-shaped gap, and wherein the method comprises the steps of: inserting the bulb into the first mold for rotational motion; using the heating means to mold the bulb into a flare shape almost identical to the flare-shaped gap; and forming the flare shape using the second mold.
This configuration can stabilize the dimensional accuracy of the flare shape.
In addition, in the flare manufacturing method for bulbs according to the present invention, when inserting the bulb into the first mold to rotatively move it by means of the rotation drive means and then using the heating means to mold the bulb into the flare shape almost identical to the flare-shaped gap, the almost identical flare shape is formed using flare formation support means having a shape almost identical to the shape of the second mold before forming the flare shape using the second mold.
According to this configuration, when the bulb has failed to expand into the almost identical flare shape despite the heating of the bulb by the heating means and the subsequent rotation of the first mold by means of the drive means, the flare formation support means enables the expansion to improve productivity.
Furthermore, in the flare manufacturing method for bulbs according to the present invention, at least one of the first and second molds has heat insulating means for maintaining temperature.
This configuration can reduce variations in mold temperature to further stabilize the dimensional accuracy of the flare shape.
A flare manufacturing apparatus for bulbs according to the present invention comprises: a first mold having a recess formed into a flare shape and rotatively moved by rotation drive means; a second mold having a projection fitted in the first mold to form a flare-shaped gap; and heating means for heating and melting a cylindrical bulb held by the first mold.
This configuration improves the dimensional accuracy of the flare shape.
In addition, in the flare manufacturing apparatus for bulbs according to the present invention, flare formation support means, which forms a flare shape almost identical to a projection of the second mold when rotated, is mounted on an index plate with the first mold.
According to this configuration, when the bulb has failed to expand into the flare shape despite the rotation of the first mold, the flare formation support means enables the expansion to improve productivity.
Furthermore, the flare manufacturing apparatus for bulbs according to the present invention has a shape recognition sensor for checking whether the glass bulb has a flare shape almost identical to that of the mold.
This configuration can check whether or not the bulb has failed to expand into the flare shape despite the rotation of the first mold.
In addition, at least one of the first and second molds has heat insulating means for maintaining temperature.
This configuration can reduce variations in mold temperature to further stabilize the dimensional accuracy of the flare shape.
As described above, by expanding the bore of the glass bulb based on the rotational force of the lower mold to form the general flare shape and then fitting the lower mold on the upper mold to form the complete flare shape, the present invention can provide a flare manufacturing method and apparatus for bulbs which has an excellent effect of stabilizing dimensional accuracy such as the outer-diameter accuracy and roundness of the flare and the concentricity between the bulb portion and the flare portion.